(a) Technical Field
Embodiments of the present invention relate generally to display devices and their driving methods. More particularly, embodiments of the present invention relate to display devices including a white pixel, and their driving methods.
(b) Description of the Related Art
Display devices such as liquid crystal displays (LCDs) and organic light emitting devices generally include a display panel that has known elements that include a plurality of pixels including switching elements and a plurality of signal lines, a gray voltage generator that generates a gray reference voltage, a data driver that uses the gray reference voltage to generate image data signals, and the like.
Each pixel includes at least one switching element and an optical conversion element connected thereto. The optical conversion element may include a liquid crystal capacitor in a case of the liquid crystal display, or may include an organic light emitting element in a case of the organic light emitting device. The optical conversion element may include a pixel electrode connected to the switching element to receive a data voltage, a common electrode for application of a common voltage, and an optical conversion layer positioned therebetween. The optical conversion layer may include a liquid crystal layer in the case of the liquid crystal display, or an organic emission layer in the case of the organic light emitting device.
The pixel electrode may be arranged in a matrix shape, and in this case, the pixel electrode is connected to a switching element such as a thin film transistor (TFT), so as to receive data voltages.
The display device generates these data voltages according to the image signal and respectively applies a data voltage and the common voltage to the pixel electrode and the common electrode, thereby displaying an image through the optical conversion element.
For full color reproduction, a plurality of pixels may include color pixels representing primary colors such as red, green, and blue, for example, a red pixel, a green pixel, and a blue pixel. The red pixel, the green pixel, and the blue pixel each represent a primary color.
However, images displayed using only colored pixels may have undesirably low luminance. Particularly, in the case of liquid crystal displays, since the red pixel, the green pixel, and the blue pixel each include colored filters, a light amount emitted from the backlight unit is reduced while passing through the color filter such that the luminance of the image may be excessively reduced. To solve this problem, the display device may further include a white pixel representing white light, in addition to the colored pixels. For example, in the case of liquid crystal displays, since the white pixel does not include a color filter, the luminance of the image may be increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.